Summary
Bluetongue (BT) virus (BTV) is a species in the genus Orbivirus of the family Reoviridae; it causes a viral disease of sheep and occasionally cattle, and is transmitted by biting midges of the genus Culicoides. BTV replicates in the haemopoeitic and endothelial cells of the blood vessels. Rarely, and only when a bull is viraemic, may BTV be recovered from semen. Serological techniques, most notably enzyme immunoassays, based on the detection of a group antigen, have been used where required in the certification of animals as ‘bluetongue-free’. The various techniques used for diagnosis are viral isolation, the enzyme-linked immunosorbent assay and the polymerase chain reaction.

Keywords
Bluetongue, Diagnosis, Sheep, Viral disease.